Microscopes often employ an immersion fluid during optical imaging. The immersion fluid (e.g., oil or the like) increases the index of refraction (as compared to air), thereby increasing the resolution of the resulting image. Conventional microscopes include complicated and cumbersome stage holders that allow for removal of a sample, delivery of immersion fluid, and replacement of the sample. Current microscopic devices that allow for replacement of immersion fluid are expensive and often minimally effective. The problem of immersion fluid loss due to shear (from rotating microscope objectives) and surface tension is particularly acute during large area scans.
For example, in many applications, samples are contained in well plates (e.g., 96 well plates) that are scanned by one or more objectives located on an inverted microscope. Immersion fluid is manually placed or interposed between the objective lens and the sample container (e.g., well plate). When the immersion fluid is lost during the scanning operation, an operator manually replaces the immersion fluid. Typically, this is done by placing a dropper or bottle tip in the small gap located between the objective lens and the specimen holder. Unfortunately, it is difficult for the operator to place the immersion fluid within this small space or gap. In addition, this process is inherently risky because during the replacement process it is possible to overfill the space with too much fluid, thereby causing spillage of the immersion fluid onto non-immersion fluid optics. In addition, fluid droppers and immersion fluid bottles are difficult to manage and often get coated by the immersion fluid which eventually finds its way onto a user's hands and/or gloves and ultimately onto the microscope optics. Moreover, conventional replacement of immersion fluid is problematic because the sample or specimen may not be moved to its original position or location after re-loading of the immersion fluid. Finally, because this process is a manual operation, the replacement of immersion fluid can significantly slow the speed at which samples may be scanned and may be a potential bottleneck for the overall imaging process.
There thus is a need for an immersion fluid applicator and method that is capable of easily and reliably placing immersion fluid between a microscopic objective lens and a sample holder. The system and method may be implemented without using the cumbersome droppers and bottles that have heretofore been used. In one preferred aspect of the invention, the immersion fluid applicator may be automatically controlled to place immersion fluid between a microscopic objective lens and a sample holder. There is a further need for an immersion fluid applicator that is able to reduce the overall amount of time required to replace lost or used immersion fluid.